Giving is self-rewarding for monkeys

Abstract

Helping and sharing among humans is often motivated by empathy and accompanied by a sense of satisfaction. To determine whether similar self-rewarding mechanisms may underpin assistance among nonhuman primates, eight female brown capuchin monkeys (Cebus apella) underwent testing in a simple choice paradigm. Paired with a partner, subjects could select either a ''selfish'' option that rewarded only themselves, or a ''prosocial'' option that rewarded both of them. Subjects systematically favored the prosocial option provided their partner was a) familiar, b) visible, and c) receiving rewards of equal value. Prosocial tendencies increased with social closeness, being lowest toward strangers and highest toward kin. That the monkeys understood the options was suggested by greater orientation to the partner during prosocial than selfish choices. Prosocial preferences were reduced by inequity, when the partner received a superior reward. If the view between both monkeys was blocked, choices became strikingly selfish. Thus, under certain conditions, delivering benefits to others seems gratifying to nonhuman primates.altruism ͉ capuchin monkey ͉ empathy ͉ inequity ͉ prosocial behavior

Donor payoffs and other-regarding preferences in cotton-top tamarins (Saguinus oedipus)

“…The authors proposed that cooperative breeding has provided a strong evolutionary force shaping other-regarding preferences, and this explains why marmosets and humans (Burkart and van Schaik 2009;Hrdy 2005) show these preferences but chimpanzees do not. This interpretation is, however, weakened based on the evidence that capuchin monkeys also show other-regarding preferences in similar tasks (de Waal et al 2008;Lakshminarayanan and Santos 2008). Thus, cooperative breeding is not necessary for the evolution of other-regarding preferences.…”

Prosocial deficits in behavioral variant frontotemporal dementia relate to reward network atrophy

“…The subjects learn that if they choose the “selfish” token, they alone receive a reward (e.g., a slice of apple), and when they choose the “prosocial” token, the subjects and their partners both receive the same reward. Monkeys typically choose the prosocial token, giving to their partners even when there is no overt benefit to themselves, which suggests that prosocial behavior is normative and inherently rewarding in highly social species (de Waal et al., 2008). …”

“…Prosocial behaviors—behaviors that prioritize the needs of others over one's own—strengthen kinship bonds, maintain group cohesiveness, promote interpersonal safety, and facilitate resource‐sharing (de Waal, 2012; de Waal & Suchak, 2010; Decety, 2011). In non‐human animals, prosociality is assessed by measuring other‐focused affiliative actions including consolation, targeted helping, cooperation, and giving (Boesch, 1994; de Waal, Leimgruber, & Greenberg, 2008; Fraser & Bugnyar, 2010; Kuczaj et al., 2015; Palagi, Paoli, & Tarli, 2004; Plotnik, Lair, Suphachoksahakun, & de Waal, 2011; Warneken, Hare, Melis, Hanus, & Tomasello, 2007). Elephants and chimpanzees use physical contact to console kin who are injured or ill, and some primates and rats give food to conspecifics when they could choose to feed only themselves (Ben‐Ami Bartal, Decety, & Mason, 2011; Burkart, Fehr, Efferson, & van Schaik, 2007; Douglas‐Hamilton, Bhalla, Wittemyer, & Vollrath, 2006; Fraser, Stahl, & Aureli, 2008; Koski & Sterck, 2009; Plotnik & de Waal, 2014).…”

“…Elephants and chimpanzees use physical contact to console kin who are injured or ill, and some primates and rats give food to conspecifics when they could choose to feed only themselves (Ben‐Ami Bartal, Decety, & Mason, 2011; Burkart, Fehr, Efferson, & van Schaik, 2007; Douglas‐Hamilton, Bhalla, Wittemyer, & Vollrath, 2006; Fraser, Stahl, & Aureli, 2008; Koski & Sterck, 2009; Plotnik & de Waal, 2014). These species engage in prosocial behaviors, therefore, because they are inherently rewarding and not because they result in personal material gain (de Waal, 2007; de Waal et al., 2008; Horner, Carter, Suchak, & de Waal, 2011; Zaki & Mitchell, 2013). …”

“…We created a new paradigm (the “Giving Game”) that was modeled after simple token‐based tasks that have been used in non‐human primates to measure prosocial giving (de Waal et al., 2008; Horner et al., 2011). Participants played the Giving Game with the experimenter and on each trial chose how much money to give to themselves and to the experimenter.…”